1. Field of the Invention
The present invention relates to a laser beam irradiation apparatus and a substrate sealing apparatus including the laser beam irradiation apparatus.
2. Description of the Related Art
A method of sealing an upper substrate and a lower substrate together using a sealant is used as a method of sealing a display device. For example, in a display device including an organic light emitting unit between an upper substrate and a lower substrate, after coating frit around the organic light emitting unit, a laser beam is irradiated onto the frit by using a laser beam irradiation apparatus, and the laser beam is moved along a sealing line of the frit by moving the laser beam irradiation apparatus. The upper substrate and the lower substrate are sealed together by hardening the frit through irradiation of the laser beam.
In this regard, when the sealing line of the frit includes a curved path having a predetermined curvature, a rotational angle of the curved path of the frit and a rotational angle of an optical tube of the laser beam irradiation apparatus must correspond to each other. If the rotational angle of the optical tube and the rotational angle of the curved path of the frit do not match, defective sealing may occur.